Old man, doctor and hunting

Something similar to this is doing the rounds on reddit - but I first heard this years ago.

An old man, in his 90s was having his bi-annual checkup at the doctors. When asked how fit and well he was feeling he said:

"I have never been better! I've got an twenty year old wife who is pregnant and having my child. What do you think about that for a person of my age!?"

The doctor though about this briefly and said "Let me tell you a story. I knew a guy who was an avid hunter and he never missed an opportunity to go out hunting. One day he left in a bit of a hurry and accidentally grabbed his umbrella instead of his gun."

The doctor continued, "He was stalking through the woods when suddenly a grizzly bear appeared in front of him! Being an experienced hunter he raised up his umbrella (thinking it was a gun), pointed it straight at the bear and squeezed the handle."

"Do you know what happened?" the doctor asked?

The old man was a bit puzzled and replied "No".

"Well", said the doctor, "the bear dropped down dead in front of him."

"That is impossible" exclaimed the old man, "someone else must have shot the bear..."

Trying to keep a professional face, the doctor replied "That is kind of what I'm getting at..."